🌞 Vet Guide to Equine Summer Sores by a Vet in 2025

By Dr Duncan Houston BVSc

1. Introduction: Don't Let Summer Soreness Spoil the Fun

Summer brings sunshine, pasture rides, and the dreaded summer sore—officially called cutaneous habronemiasis. These stubborn, itchy lesions caused by errant stomach‑worm larvae can ruin your horse’s comfort and performance. In this 2025 vet guide, I’ll walk you through what causes them, how to spot them early, manage them effectively, and prevent them from coming back, keeping your horse happy all season long. 🐎🌿

2. What Are Summer Sores?

Summer sores are ulcerative, inflamed lesions caused by the larvae of the stomach worms Habronema and Draschia. These larvae are transported to your horse’s skin by flies when they land on wounds or sensitive areas. Instead of being swallowed, the larvae embed and cause intense inflammation, yellow “sulfur granules,” and persistent itching :contentReference[oaicite:3]{index=3}.

3. Life Cycle of the Culprits 🪰

Here’s how it works:

1. Adult worms live in the horse’s stomach and shed eggs via feces.
2. Eggs hatch in manure; fly maggots ingest larvae, which develop to infective L3 stage inside flies.
3. Flies land on wounds or mucous areas and deposit larvae onto skin.
4. Larvae can cause stomach infection if swallowed, or cutaneous disease if embedded in skin :contentReference[oaicite:4]{index=4}.

4. Typical Locations & Signs

Summer sores appear on moist or injured areas such as:

• Lower legs (pasterns)
• Around eyes and lips
• Genital region (prepuce/vulva)
• Any stubborn wounds

Signs include ulceration, crusting, yellow granular discharge, severe pruritus, and proud granulation tissue :contentReference[oaicite:5]{index=5}.

5. Diagnosis: Early Recognition Is Key

Veterinary diagnosis may involve:

• Clinical history & lesion appearance—seasonal onset, persistent sore.
• Biopsy to confirm larvae or rule out sarcoids, SCC or fungal diseases :contentReference[oaicite:6]{index=6}.
• PCR testing when larvae are not visible :contentReference[oaicite:7]{index=7}.

6. Treatment Strategies

Most small sores respond to combined therapy:

• Macrocyclic lactones like ivermectin or moxidectin—single oral dose, often repeated—for larval kill :contentReference[oaicite:8]{index=8}.
• Anti‑inflammatory therapy: topical steroids, intralesional corticosteroids (e.g. triamcinolone), or NSAIDs to reduce hypersensitivity :contentReference[oaicite:9]{index=9}.
• Wound care: gentle cleansing, anti‑microbial dressings, bandaging to block flies :contentReference[oaicite:10]{index=10}.
• Surgical or cryotherapy debridement for large or proud lesions :contentReference[oaicite:11]{index=11}:contentReference[oaicite:22]{index=22}.

7. Fly Control: The Preventive Champion

Flies are the essential link—eliminate them, and you break the cycle:

• Fly masks, sheets, and boots during peak seasons :contentReference[oaicite:12]{index=12}.
• Barn misting, residual sprays, sticky traps, and fans :contentReference[oaicite:13]{index=13}.
• Remove manure twice weekly; clean bedding/feed; use feed-through and biological controls :contentReference[oaicite:14]{index=14}.

8. Prevention Protocol

• Routine deworming program including ivermectin/moxidectin during fly season :contentReference[oaicite:15]{index=15}.
• Prompt management of skin wounds: clean, cover, and treat immediately :contentReference[oaicite:16]{index=16}.
• Maintain year-round fly control and pasture hygiene :contentReference[oaicite:17]{index=17}.
• Veterinary follow-up for persistent or recurrent sore horses—the lesions may recur due to hypersensitivity or genetic predisposition :contentReference[oaicite:18]{index=18}.

9. Prognosis & Recurrence

With timely treatment and hygiene, lesions typically heal by season’s end. Horses with prior summer sores often experience recurrence and become seasonal sufferers. But a smart preventive strategy keeps them comfortable year after year :contentReference[oaicite:19]{index=19}.

10. Case Study: “Shadow” the Lesson

Shadow, a gelding with a persistent pastern ulcer in June, underwent oral ivermectin, topical steroids with silver dressing, and was fitted with a fly boot. Within 3 weeks the lesion shrank dramatically and flew-free bandaging allowed full healing by late summer. With seasonal deworming, his summer remained sore-free the next year.

11. Ask A Vet Guidance & Support 🩺

At Ask A Vet, we partner with owners to manage and prevent summer sores. Our services include tele‑health consultations, personalized deworming plans, advice on fly control regimes, wound‑care tutorials, and 24/7 messaging. Download the Ask A Vet app to connect with a professional vet in moments of need.

12. Quick Reference Table

13. Frequently Asked Questions (FAQs)

❓ Are summer sores contagious between horses?

No direct horse‑to‑horse transmission—it requires a fly vector and skin wound :contentReference[oaicite:20]{index=20}.

❓ Can they resolve without treatment?

Yes, small sores sometimes resolve in cooler weather—but treatment is faster, more comfortable, and prevents spreading.

❓ Do I need surgery?

Only for large lesions or persistent proud flesh that block healing. Most cases respond to medications and bandaging.

14. Summary & Final Thoughts

• Summer sores are seasonal but preventable with smart management.
• Early intervention with dewormers, anti‑inflammatories, wound protection, and fly control is vital.
• Recurring cases need veterinary oversight, deworming, and fly strategies.
• Team up with Ask A Vet anytime for peace of mind and expert care.

With the right plan in place, your horse can enjoy itch‑free summers. Don’t let these pesky sores spoil their season—partner with us at Ask A Vet for personalized, professional support. Download the Ask A Vet app today! ❤️